Nebulization-humidification nozzle

ABSTRACT

A nozzle formed by the mating of two separable parts, a housing and a plug insert, having a smaller diameter orifice formed at a first mating interface of these two parts, a Venturi chamber connected to the smaller orifice, being formed at a second mating interface of these two parts and a larger diameter orifice extending through the plug insert part being connected to the Venturi chamber.

BACKGROUND OF THE INVENTION

Nozzles used in humidifier and nebulizer atomizers are often of theVenturi type. These Venturi nozzles usually have a small orifice throughwhich a gas is forced to cause its expansion. The expanding gas jet isdirected through, or over, a Venturi chamber containing a fluid wherebyan effected vacuum draws droplets into the gas stream. This mixture isusually passed through a second or larger orifice permitting a secondaryexpansion during which droplet groupings tend to disassociate. Theaerosol mixture may then be impinged upon a baffle to further reduce thesize of droplets in suspension before being passed out of the device.

Three components, and their associated dimensions, are essential to thedesign of these nozzles. These components include a smaller or jetorifice, with its jet diameter; a larger or aerosol orifice, with itsaerosol diameter; and a Venturi chamber, with its spacing between thejet and aerosol orifices. Additionally, it is critical that thecenterline of the aerosol orifice be aligned with the centerline of thejet orifice in an assembled nozzle. Any deviation from specificationgreatly affects nozzle performance.

The manufacture of high quality, nebulization nozzles (those capable ofproducing a mist in the 1 to 10 micron size) therefore becomes quitecostly with quality control expenses becoming a significant part ofoverall nozzle costs. These expenses have hampered the development ofdisposable nozzles.

A principal problem in making these nozzles out of materials acceptablefor medical application, such as molded plastic materials, arises in themolding of the interior cavity. This cavity is usually formed with along pin, used as the die, which is frequently about one-eighth inch indiameter. The pin has a stepped-down portion which is used to form thejet orifice. This thin stepped-down portion is usually driven into themolding material intended to form the housing of the nozzle. Thematerial is penetrated to its full depth, or alternatively, through itsfull depth and beyond. During this operation the pin often bendsslightly and wears a side of the formed hole. Sometimes the pin breaksoff in the hole. In many instances, therefore, an irregular hole resultsfrom the manufacturing process. Moreover, as a result of this process"molding flash" is often generated which extends into intendedpassageways. When the pin penetration is only to full depth, a "skin" isoften left over the end of the molded hole. In addition, the thinstepped-down end of the pin has a tendency to move off of center duringthe molding process thus producing a misalignment of jet orifice toaerosol orifice in an assembled nozzle.

These molding process defects contribute to high rejection rates,increase mold costs, increase mold maintenance costs, and increasequality control costs.

What is desired, therefore, is a method of manufacturing these nozzlesin which the enumerated problems and defects are eliminated or reducedso that the nozzle produced is economical enough to be disposable.

An object of this invention is to provide a method of manufacturingVenturi type nebulization nozzles wherein molding skin and flash defectsare reduced.

Another object of this invention is to provide a method of manufacturingsaid nozzles wherein misalignment of orifices defects are reduced.

A further object of this invention is to provide an nebulization nozzlewhich is economically disposable.

Another object of this invention is to provide a disposable nozzlehaving a reduced number of parts.

Another object of this invention is to provide a disposable nozzlehaving essential functions defined at the interfaces of two matingparts.

An even further object of this invention is to provide a disposablenozzle wherein the essential functions defined at mating part interfacesare defined by mating part interfaces.

SUMMARY OF THE INVENTION

The objectives of this invention may be achieved by the manufacturing ofan nebulization nozzle in two separable parts wherein a nozzle may becreated by the mating of the two components, a housing and a pluginsert. Nozzle functions may be established at, and by, interfacingsurfaces. The components may be injection molded of thermoplasticmaterials.

The housing is preferably molded with a passageway therethrough havingan annular-like groove or undercut in the designated exit end of thispassageway.

The plug insert is preferably molded having a mushroom-like shape with anarrower stem portion and a wider head portion. Preferably, alongitudinal channel runs the length of the stem portion. A firstpassageway may extend through the head portion in alignment with thecenterline of the stem channel, while a second hole may extend throughthe head for providing access to the passageway's annular groove whenthe plug is inserted into the housing.

A nozzle may be assembled by inserting the stem portion of the pluginsert into the housing passageway at the groove end until the headportion of the plug abuts the housing exit end. With the componentsmated within close tolerances, a jet orifice may exist at thepassageway-stem interface, with the longitudinal channel and passagewayinner wall defining the size and shape of the jet orifice. The headportion through passageway having been molded into the plug insert partin alignment with the stem channel may form an aerosol orifice which isin alignment with the formed jet orifice. A Venturi chamber may beformed at the passageway annular groove and plug head interface, withthe groove width defining the spacing from jet orifice to aerosolorifice.

DESCRIPTION OF THE DRAWINGS

The novel features of this invention, as well as the invention itself,both as to its organization and method of construction, will best beunderstood from the following description taken in connection with theaccompanying drawings in which like characters refer to like parts, andin which:

FIG. 1 is a cross-sectional view of the housing component of the nozzle;

FIG. 2 a and b shows a perspective view and a cross-sectional view,respectively, of the plug insert component;

FIG. 3 shows a cross-section of an assembled nozzle with an alternateembodiment of the plug insert;

FIG. 4 shows a cross-section of an alternate embodiment of the nozzle ina nebulizer apparatus.

DETAILED DESCRIPTION OF THE INVENTION

A disposable nebulizer nozzle of the kind used in medical humidifiersand nebulizers needs to be inexpensive. This factor necessitates thatmanufacturing costs and material costs be low. A simple design with aminimum number of parts contributes to lowering these factors. Asimplified manufacturing process also helps.

The following essential ingredients contribute to a Venturi-typenebulization nozzle, which is commonly employed in medical applications;a small diameter air jet being formed by air forced through a smallorifice, a passing of the air jet through or by a fluid containingVenturi chamber, and the exiting the air stream through a largerorifice. As the air passes the fluid, most likely water, an ejectoraction is created establishing the Venturi chamber's operations anddroplets of the fluid are drawn into the air jet by the vacuum. The airjet carries the suspended droplets through the larger orifice as a mist.Nozzle performance characteristics are therefore determined by the smallor jet orifice size, the larger or aerosol orifice size, the distancebetween orifices, and the air jet velocity.

For a given nozzle specification, various product defects can be createdduring a typical manufacturing process, such as the injection molding ofthermoplastic material as is commonly employed for medical apparatus.These defects can alter nozzle operating characteristics sufficiently toproduce a defective or rejectable nozzle. Typical defects include skinand flash in and around the jet and aerosol orifices, misalignment ofthe jet and aerosol orifices and distortion in jet and aerosol orificewalls.

A nozzle design and a molding process wherein the cavities to be formedare at or close to outer surfaces or are of simple and"straight-through" configuration tends to greatly reduced rejectableproducts. Moreover, when the dies employed can be designed of sufficientsize and strength or can have sufficient support, a better manufacturedproduct will result.

FIGS. 1 and 2 show the components of a simplified nozzle having only twoparts, a housing 10 and an insertable plug 20.

The housing 10 is shown in cross-section in FIG. 1. This housing 10 maybe formed from a mass of molded plastic such as polyethylene orpolypropylene to have a support member 11. A passageway 13, which mayhave any one of a plurality of acceptable shapes, extends completelythrough the support member 11. Preferably, the passageway 13 iscylindrical in shape with a circular cross-section. At one end of thepassageway 13, designated the exit end, a groove or undercut 15 extendsannularly about the passageway 13 wall. As with the passageway 13, thegroove 15 may have any of a number of shapes. It is convenient, however,that groove 15 be cylindrically shaped and extend inwardly from the exitedge of housing 10 to a designated design depth so as to extendannularly about the passageway 13.

The exit wall 17 of the housing 10 extends perpendicularly, in a flatplane, to the passageway 13; and is large enough to provide an air andfluid seal when mated with a surface of the plug insert 20.

The entrance wall of the housing 10, i.e., opposite the designated exit,may be provided with a protruding tapered fitting 19 or the like towhich an air supply may be fitted.

The plug insert 20, FIGS. 2 a and b, includes a stem portion 21 and ahead portion 23. Since the plug insert 20 mates with the passageway 13its shape is governed by that of the passageway 13. For a cylindricalhousing passageway 13, the plug insert 20 is mushroom-shaped, having acylindrically-shaped stem 21 and a wider, cylindrically-shaped head 23.

Extending longitudinally along the surface of the stem 23 is a channel25. The channel 25 may have a number of cross-sectional shapes includingsemicircular, vee-shaped or even be a cordal-section formed by a flatalong the stem 21. However, since the shape of the channel 25contributes to the shape of the jet orifice in an assembled nozzle, thecross-section of this channel will effect nozzle performance. Thechannel 25, preferably, has a semicircular cross-section.

Extending through the head 23 of the plug insert 20, and beyond, inalignment with the centerline of the channel 25, is a circularpassageway 27. The passageway 27 extends along the stem 21 beyond thehead 23 a distance equal to the extension of the annular groove 15, fromthe exit wall of housing 11 along the housing passageway 13. Thisextension of the passageway 27, beyond the plug head 23, carves out anenlarged semicircular-like cavity 27 along the stem 21 which meets thechannel 25. The diameter of this passageway 27 greatly exceeds thecross-sectional dimensions of the stem groove 25.

Positioned away from the head 23 through passageway 27 is a secondpassageway or hole 29. The hole 29 may be circular, or of any otherconvenient cross-sectional shape; and extends into a tangential plane tothe circumference of the stem 21. Preferably the hole 29 is positioned180 degrees about the stem 21 from the passageway 27. While this hole29, alternately, may be canted, its inner end should remain positionedtangent to the stem 21 surface.

The housing 10 may therefore be easily injection molded with acylindrical pin-shaped die to produce a product with a minimum ofmanufacturing defects. This pin may have an outer diameter equal to thediameter of the passageway 13 with a built-up shoulder to form thegroove 15. In that the diameter of the passageway 13 and the diameteracross the annular groove 15 are not critical, a practical size may bechosen for these dimensions which allows for a substantial pin (die)while maintaining the size of the housing 10 within a reasonable range.Under these conditions the molding defects discussed above are greatlyreduced.

Moreover, the substantial size of this pin (die) allows for a carefulmachining of the length of the built-up shoulder which forms thecritical Venturi spacing.

The plug insert 20 may be injection molded having the stem channel 25formed by a machined key on the inner surface of the mold. The hole 29which is used to feed fluid to the annular groove 15 and therein to theVenturi chamber may be formed by a pin member of reasonable size. Thealignment of this hole 29 in a tangent plane to the circumference of thestem 21 or the canting of this hole 29 out of the plane whilemaintaining in inner end of the hole tangent to the stem 21 surface isessential, the exact size of the hole 29 and rotated position about thestem 21 is not.

The aerosol orifice or head passageway 27 needs to be formed to exactdimensions of diameter and depth and positional alignment. Thedimensions of a pin which forms this passageway 27 must be precise. Inthat the aerosol orifice is of considerable size, relative to the jetorifice, the passageway 27 can be formed with a pin sturdy enough toproduce an acceptably manufactured passageway 27. These manufacturingconditions contribute to a product having a greatly reduced incidence ofmanufacturing defects.

An assembled nozzle is shown in FIG. 3 in cross-section about the exitend of the housing 10. With the plug 20 inserted into the exit end ofthe housing 10, i.e., the stem portion 21 being inserted to fullestdepth until the head 23 buts against the exit wall 17, essentialfunctional components are formed at, and by, interfacing surfaces whichmate within close tolerances. The jet orifice is formed at, and by, themating interface of the housing passageway 13 and the stem channel 25.The Venturi chamber is formed at, and by, the mating interface of thehousing annular groove 15, the head 23 inner or housing-facing surfaceand the passageway 27. The passageway 27 through the head 23 creates anaerosol orifice.

In the embodiment as shown in FIG. 3 the stem portion has been truncatedto reduce the length of the channel 25. Also, the center of the stem 21has been hollowed to permit a savings in material. Additionally, thehole 29 has been fitted with a connection fitting 31 for connecting to awater supply.

In operation, air is forced through the nozzle's jet orifice from theentrance end of the housing 10; through the Venturi chamber, which hasbeen supplied water via the fitting 31, the hole 29 and the annulargroove 15, to extract droplets of water and to propel them through theaerosol orifice 27 to create an output mist.

An alternate embodiment of the nozzle is shown in FIG. 4. In thisalternate embodiment, housing 30 contains a cylindrically-shapedpassageway 31 and a tapered fitting 33 for inlet air in similarconfiguration to that of the previously described housing 10. However,in this embodiment the annular groove, which provides the Venturichamber spacing, does not exist as part of the housing 30. Venturichamber spacing is provided by an annular groove in a plug insert 40 andwill be further discussed below. Formed as part of the housing 30 is awater reservoir 35 which is positioned below and away from thepassageway or housing exit wall 37. This water reservoir 35 is formed bya continuation of this housing exit wall 37, the housing passageway 31being in a horizontal position, downwardly and then outwardly in aflaired or cup fashion.

In this alternate embodiment a plug insert 40, again, has amushroom-like configuration with a cylindrically-shaped stem portion 43having a truncated end and a cylindrically-shaped head portion 45extending beyond the stem 43. A semicircular channel 47 again extendslongitudinally along the stem 43. The plug 40 has the head portion 45with an elongate extention 49 on one side. This extension 49 is intendedto extend downwardly into the water reservoir 35 when the plug 40 isinserted into the housing 30.

Extending through the head 45 in alignment with the channel 47 is acircular passageway 51. As in other embodiments, the function of thispassageway 51 is to form the aerosol orifice of the nozzle.

Spaced about the head in a plane perpendicular to the stem 43 so as toconnect to the channel 45 and the circular passageway 51 is a groove 41.This groove 41 provides the Venturi chamber spacing and connects to awater passageway 53 formed between the head extension 49 and the housingexit wall 37 when the plug 40 is fully inserted into the housing. Aswith other embodiments, the insertion of the plug 40 into the housing 30creates the jet orifice and the Venturi chamber.

Many changes could be made in this invention without departing from thescope thereof. All matter contained in the above designation or shown inthe accompanying drawings is therefore to be interpreted as illustrativeand not to be taken in the limiting sense.

What is claimed:
 1. A nozzle having a plurality of parts creating a jetorifice, an aerosol orifice and a Venturi chamber connectedtherebetween, comprising:means for creating the jet orifice at a firstmating interface of said parts; means for creating the Venturi chamberat a second mating interface of said parts, said Venturi chamber beingso created connected to said jet orifice; and means for establishing aVenturi chamber supply passageway at a third mating interface of saidparts, said supply passageway being connected to said Venturi chamber.2. The apparatus of claim 1 wherein:said jet orifice creating meansaccomplishes said creation by a first interfacing of parts; said Venturichamber creating means accomplishes said creation by a secondinterfacing of parts; and said supply passageway establishing meansaccomplishes said establishment by a third interfacing of parts.
 3. Theapparatus of claim 2 wherein said plurality of parts includes:a housing;and a plug insertable therein.
 4. The apparatus of claim 3 wherein saidhousing includes:a passageway; and an annular groove extending aboutsaid passageway at one end thereof.
 5. The apparatus of claim 4 whereinsaid plug includes a stem portion and a head portion connected thereto,said stem being insertable into said housing passageway, said headbutting against the passageway housing wall when said stem is fullyinserted to seal the end of the housing passageway.
 6. The apparatus ofclaim 5 wherein said stem portion includes:a longitudinal channel in thesurface thereof; and a cavity extending along said stem in alignmentwith said channel, said cavity's extension meeting said channel and thejointure of said stem and said head portions.
 7. The apparatus of claim6 wherein said head portion includes a first passageway extendingtherethrough, said passageway being in alignment with said stem channeland said stem cavity.
 8. The apparatus of claim 7 wherein said headportion includes a second passageway therethrough, being positioned adistance away from said first passageway and having an inner end tangentto said stem surface.
 9. The apparatus of claim 8 wherein said housingpassageway, said plug head first and second passageways have circularcross-sections; wherein said stem channel and said stem cavity havesemicircular cross-sections; and wherein said housing annular groove iscylindrically-shaped.
 10. A nozzle having plural parts, comprising:ahousing containing a passageway therethrough; and a plug beinginsertable into said passageway, creating at interfacing surfacestherebetween a jet orifice, a Venturi chamber in alignment with said jetorifice and a supply passageway connected to said Venturi chamber, saidplug also including an aerosol orifice therethrough in alignment withsaid jet orifice and said Venturi chamber created.
 11. The nozzle ofclaim 10 wherein said passageway includes a larger cross-section at oneend thereof and wherein said plug is insertable at said passagewaylarger end.
 12. The nozzle of claim 11 wherein said plug includes:a stemportion, having a channel extending along the surface thereof and beinginsertable into said housing passageway larger end; and a head portionbeing larger in cross-section than said stem and sealing the end of saidpassageway when said stem portion is fully inserted therein, said headportion having a first passageway in alignment with said stem channeland a second passageway, spaced away from said first passageway, saidstem portion also including a cavity connecting said stem portionchannel and said head portion first passageway.
 13. The nozzle of claim12 wherein said housing passageway larger cross-sectional end includesan annular groove.
 14. The nozzle of claim 10 wherein said housingincludes a reservoir external to said passageway; and wherein said plugincludes a stem portion having a channel extending along the surfacethereof and being insertable into said housing passageway, and a headportion being larger in cross-section than said stem and sealing the endof said passageway on one side thereof, the other side of said headbeing elongate to extend along the outer face of said housing toproximity of said reservoir to form a passageway from said reservoir,said head portion also including a passageway therethrough in alignmentwith said stem portion channel and a groove creating a chamber betweensaid through passageway and said stem portion channel, said groove beingconnected to the passageway formed from said reservoir by said housingand said head portion elongate extension.